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PubMed2006

Both carboxy-terminus NES motif and mutated tryptophan(s) are crucial for aberrant nuclear export of nucleophosmin leukemic mutants in NPMc+ AML.

We recently identified aberrant cytoplasmic expression of nucleophosmin (NPM) as the immunohistochemical marker of a large subgroup of acute myeloid leukemia (AML) (about one-third of adult AML) that is characterized by normal karyotype and mutations occurring at the exon-12 of the NPM gene. In this paper, we have elucidated the molecular mechanism underlying the abnormal cytoplasmic localization of NPM. All 29 AML-associated mutated NPM alleles so far identified encode abnormal proteins which have acquired at the C-terminus a nuclear export signal (NES) motif and lost both tryptophan residues 288 and 290 (or only the residue 290) which determine nucleolar localization. We show for the first time that both alterations are crucial for NPM mutant export from nucleus to cytoplasm. In fact, the cytoplasmic accumulation of NPM is blocked by leptomycin-B and ratjadones, specific exportin-1/Crm1-inhibitors, and by reinsertion of tryptophan residues 288 and 290, which respectively relocate NPM mutants in the nucleoplasm and nucleoli. NPM leukemic mutants in turn recruit the wild-type NPM from nucleoli to nucleoplasm and cytoplasm. These findings indicate that potential therapeutic strategies aimed to retarget NPM to its physiological sites will have to overcome 2 obstacles, the new NES motif and the mutated tryptophan(s) at the NPM mutant C-terminus.

Active Transport, Cell Nucleus↗

PubMed2006

Clinical implications of FLT3 mutations in pediatric AML.

Activating mutations of the FLT3 gene occur because of an internal tandem duplication of the juxta-membrane domain (FLT3/ITD) or point mutation of the activation loop domain (FLT3/ALM). The presence of FLT3 mutations as well as the allelic ratio of FLT3/ITD (ITD-AR, mutant-wild type ratio) may have prognostic significance. FLT3 mutation status of 630 children with de novo acute myeloid leukemia (AML) treated on CCG-2941 and -2961 was determined, and ITD-AR was calculated for patients with FLT3/ITD. Clinical characteristics and outcomes for patients with FLT3/ALM and FLT3/ITD at varying ITD-ARs was determined and compared with those without FLT3 mutations (FLT3/WT). FLT3/ITD and FLT3/ALM were detected in 77 (12%) and 42 (6.7%) of the patients. Progression-free survival (PFS) was similar in patients with FLT3/ALM and FLT3/WT (51% versus 55%, P = .862). In contrast, PFS at 4 years from study entry for patients with FLT3/ITD was inferior to that of patients with FLT3/WT (31% versus 55%, P < .001). PFS decreased with increasing FLT3/ITD-AR (P < .001), and those with ITD-AR greater than 0.4 had a significantly worse PFS than those with lower ITD-AR (16% versus 72%, P = .001) or with FLT3/WT (55%, P < .001). ITD-AR defines the prognostic significance in FLT3/ITD-positive AML, and ITD-AR greater than 0.4 is a significant and independent prognostic factor for relapse in pediatric AML.

Adolescent↗

PubMed2006

Newly identified c-KIT receptor tyrosine kinase ITD in childhood AML induces ligand-independent growth and is responsive to a synergistic effect of imatinib and rapamycin.

Activating mutations of c-KIT lead to ligand-independent growth. Internal tandem duplications (ITDs) of exon 11, which encodes the juxtamembrane domain (JMD), are constitutively activating mutations found in 7% of gastrointestinal stromal tumors (GISTs) but have not been described in childhood acute myeloid leukemia (AML). DNA and cDNA from 60 children with AML were screened by polymerase chain reaction (PCR) for mutations of the JMD. A complex ITD (kit cITD) involving exon 11 and exon 12 was identified with a relative frequency of 7% (4/60). The human kit cITDs were inserted into the murine c-Kit backbone and expressed in Ba/F3 cells. KIT cITD induced factorindependent growth and apoptosis resistance, and exhibited constitutive autophosphorylation. KIT cITD constitutively activated the PI3K/AKT pathway and phosphorylated STAT1, STAT3, STAT5, and SHP-2. Imatinib (IM) or rapamycin (Rap) led to complete inhibition of growth, with IC50 values at nanomolar levels. IM and Rap synergistically inhibited growth and surmounted KIT cITD-induced apoptosis resistance. IM but not LY294002 inhibited phosphorylation of STAT3 and STAT5, suggesting aberrant cross talk between PI3K- and STAT-activating pathways. The findings presented may have immediate therapeutic impact for a subgroup of childhood AML-expressing c-KIT mutations.

Acute Disease↗

PubMed2006

Rapamycin derivatives reduce mTORC2 signaling and inhibit AKT activation in AML.

The mTOR complex 2 (mTORC2) containing mTOR and rictor is thought to be rapamycin insensitive and was recently shown to regulate the prosurvival kinase AKT by phosphorylation on Ser473. We investigated the molecular effects of mTOR inhibition by the rapamycin derivatives (RDs) temsirolimus (CCI-779) and everolimus (RAD001) in acute myeloid leukemia (AML) cells. Unexpectedly, RDs not only inhibited the mTOR complex 1 (mTORC1) containing mTOR and raptor with decreased p70S6K, 4EPB1 phosphorylation, and GLUT1 mRNA, but also blocked AKT activation via inhibition of mTORC2 formation. This resulted in suppression of phosphorylation of the direct AKT substrate FKHR and decreased transcription of D-cyclins in AML cells. Similar observations were made in samples from patients with hematologic malignancies who received RDs in clinical studies. Our study provides the first evidence that rapamycin derivatives inhibit AKT signaling in primary AML cells both in vitro and in vivo, and supports the therapeutic potential of mTOR inhibition strategies in leukemias.

Adaptor Proteins, Signal Transducing↗

PubMed2001

The predictive value of hierarchical cytogenetic classification in older adults with acute myeloid leukemia (AML): analysis of 1065 patients entered into the United Kingdom Medical Research Council AML11 trial.

Acute myeloid leukemia (AML) in older adults carries a poor prognosis, and the optimum treatment remains to be determined. In younger patients, treatment stratification is frequently based upon diagnostic karyotype, which was the most important prognostic factor in the UK Medical Research Council (MRC) AML10 trial. Considered here is whether karyotype is also predictive in older adults; this is done by studying 1065 cases from MRC AML11 (median age, 66 years). Three prognostic groups were distinguished on the basis of response to induction therapy and overall survival (OS). Those with t(15;17), t(8;21), or inv(16) composed the favorable risk group. Overall, these abnormalities predicted a superior complete remission (CR) rate (72%), reflecting relatively low levels of resistant disease (RD) (8%), and lower relapse risk (RR) (56%) associated with superior OS (34% at 5 years). Normal karyotype (CR, 63%; RD, 17%; RR, 78%; OS, 15%) and other noncomplex abnormalities (CR, 53%; RD, 32%; RR, 85%; OS, 10%) composed the intermediate group; while complex karyotype predicted an extremely poor prognosis (CR, 26%; RD, 56%; RR, 91%; OS, 2%). Combining MRC AML10 and AML11 (n = 2677) revealed that the most favorable changes were rarer in older patients (younger than 55 years, 24%; 55 years or older, 7%), while complex abnormalities were more common (6% vs 13%). This study suggests that hierarchical cytogenetic classification identifies biologically distinct subsets of AML that are represented in all age groups. Furthermore, it highlights the importance of karyotype as a critical independent determinant of outcome in older patients with AML, providing a potential framework for stratified treatment approaches.

Adult↗

PubMed2000

Flow cytometric immunophenotypic characterization of pediatric and adult minimally differentiated acute myeloid leukemia (AML-M0).

We reviewed the clinicopathologic and immunophenotypic profiles of 7 pediatric and 11 adult minimally differentiated acute myelogenous leukemias (AML-M0). We also compared and evaluated myeloperoxidase in leukemic blasts using standard cytochemical and polyclonal antibody immunohistochemical stains. No distinctive clinical findings were noted in either patient group; however, thrombocytopenia typically was more prominent in adults. Adult AML-M0 also was associated with an immature myeloid profile (CD34+, terminal deoxynucleotidyl transferase positive, CD13+, and CD33+), in contrast with pediatric AML-M0, which usually lacked terminal deoxynucleotidyl transferase or CD34 but expressed bright CD33 with weak or negative CD13. Coexpression of the T-cell-associated antigen CD7 was observed in both groups. Antibody immunohistochemical stains were more sensitive than cytochemical stains for detection of myeloperoxidase activity and a useful adjunct for establishing a diagnosis of myeloid leukemia in paraffin-embedded marrow tissues.

Adolescent↗

PubMed2001

MDR-1 expression and deletions of chromosomes 7 and 5(Q) separately indicate adverse prognosis in AML.

In order to assess any correlation between MDR-1 expression and chromosomal aberrations, and to define their impact on clinical outcome in newly diagnosed AML pts, we investigated bone marrow and peripheral blood samples of 49 consecutive pts admitted to our hospital. Monosomy 7, trisomy 8 and 5q- were evaluated by means of interphase fluorescence in situ hybridization (FISH). Monosomy 7 was present in 6 pts, trisomy 8 in 5 pts, and 5q- in 6 pts. More than one aberration was seen in 7 pts. Chromosomal aberrations were mostly found in older pts (12/14 >60 years; p=0.03) and in pts with CD34 positive leukemic blasts (13/14 coexpressed CD34, p=0.0004). In 25 pts also standard G-banding analysis was performed leading to concordant results regarding chromosomes 7, 8 and 5. Flow cytometry identifyed MDR-1 positivity (MDR+) in 16 pts. MDR-1 expression appeared to be a characteristic feature in CD34+ AML (12/16 were CD34+ and MDR+ pts; p=0.013). No correlation, however, was found between chromosomal aberrations and MDR-1 expression. Pts with aberrations of either chromosomes 7, 8 or 5 detected by FISH (FISH+) were predominantly resistant to induction therapy (6/8 pts, p=0.004). A lower rate of complete remission (CR) was also seen in pts with MDR-1 expression (p=0.006). MDR+/FISH+ pts (n=3) were all refractory to remission induction, while all MDR-/FISH- pts (n=19) achieved CR (p=0.0006). MDR-1+ as well as pts with aberrations of chromosomes 7, and 5(q) showed a significantly decreased probability of overall survival. In conclusion, MDR-1 expression as well as abnormalities of chromosomes 7, and 5(q) predict poor clinical outcome in AML. The identification of these prognostic factors provides useful information for risk adapted treatment strategies.

Adult↗

PubMed1999

Isolated tetrasomy 8 in minimally differentiated acute myeloid leukemia (AML-M0).

Tetrasomy 8 as a sole anomaly in hematological disorders is relatively rare. To the best of our knowledge, only 19 such cases have been described in the literature to date. Of them, acute myeloid leukemia (AML) in 13 (M1, one; M2, three; M4, one; M5, eight), acute lymphoblastic leukemia(ALL) in one, myelodysplastic syndrome(MDS) in 3, polycythemia vera(PV) and myelofibrosis(MF), one case each. Their median survival was 20 weeks. Here, we report the first case of a 29-year-old man with minimally differentiated AML (AML-M0) displaying a tetrasomy 8 clone. Immunophenotyping showed positivity with CD33, CD34 and intracellular MPO, but all lymphoid markers tested were negative. Conventional cytogenetics of bone marrow cells showed 84.9% of metaphases with tetrasomy 8 in addition to 15.1% with normal diploidy. However, Fluorescence in situ hybridization(FISH) using a centromeric probe specific for chromosome 8 revealed trisomy 8 in 14.2% of interphase nuclei besides tetrasomy 8 in 82.4%. The patient died four weeks after diagnosis without therapy. In conclusion, these findings suggest that tetrasomy 8 is associated with a heterogeneous group of myeloid disorders and heralds a bad prognosis. It may be a consequence of clonal evolution of trisomy 8.

Acute Disease↗

PubMed1999

Relevance of in vitro leukaemia cell survival to short- and long term clinical outcome in AML.

In ninety-three cases of newly diagnosed acute myeloid leukaemia (AML) we investigated the importance to short- and long term clinical outcome of the in vitro short term leukaemia cell survival as measured by a 4-day MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide)-assay. In 67 patients treated by intravenous remission induction therapy we found that patients who after the first induction cycle or after induction therapy overall achieved a complete remission (CR) had leukaemia cells with significantly lower in vitro cell survival ability than cells of non-responders (p = 0.02 and 0.06, respectively). These relations remained statistically significant in subsequent multivariate analyses. Likewise, a favourable effect of low in vitro leukaemia cell survival on overall survival of the patients was detected in the (largest) subgroup of adult patients treated uniformly by the same remission induction regimen as well as in all patients. However, in the 44 patients, who achieved CR, the in vitro leukaemia cell survival did not show significance to remission duration or time to first relapse. Furthermore, the leukaemia cell survival (MTT-assay) did not to correlate with the Bcl-2 expression level (quantitative flow cytometry) of the leukaemia cells (r = 0.18, n = 34, p = 0.32). In addition, in a cell line model employing the growth factor dependent MO7 human AML cell line, growth factor withdrawal was associated with rapid onset of cellular apoptosis as evaluated by morphology, occurrence of a subG1 peak in DNA histograms, and loss of cellular activity in the MTT-assay. In contrast, a more moderate decline in Bcl-2 expression and gradual loss of ability to exclude the trypan blue dye was seen in the leukaemia cells in response to growth factor withdrawal. We conclude, that the MTT-assay provides a simple and sensitive method for measuring in vitro cell survival. The differences in leukaemia cell survival seen in AML may well be clinically relevant and may help to provide a better understanding of clinical drug resistance.

Acute Disease↗

PubMed2026

Coagulation activation is associated with genomic-instability-related features in TP53-mutated AML and MDS: routine laboratory patterns beyond classical disseminated intravascular coagulation.

BACKGROUND: Disseminated intravascular coagulation (DIC) is a serious complication of acute myeloid leukemia (AML) associated with poor prognosis. In TP53-mutated AML and myelodysplastic syndrome (MDS), however, the classical ISTH criteria rarely identify overt DIC, although bleeding and thrombotic complications are well documented in acute leukaemia. We hypothesized that these patients exhibit a lower-grade, subclinical coagulation activation that is associated with the underlying genomic-instability-related features of TP53-mutant disease. METHODS: We retrospectively analyzed 107 consecutive patients with TP53-mutated AML (n = 52) or high-risk MDS (MDS, n = 55), median age 65 years, diagnosed and initially evaluated at our centre between 2018 and 2025. Seven routine coagulation markers and 46 co-mutated genes were evaluated for associations with overall survival (OS) using univariate and multivariable Cox regression, continuous dose-response modeling, and unsupervised k-means clustering. Internal validity was assessed by 1000 bootstrap resamples. RESULTS: Overt DIC according to ISTH criteria was rare (15%). Subclinical activation was common: 50% of patients had a D-dimer ≥1 μg/mL, 41% a fibrinogen ≥4 g/L, and 29% an INR ≥1.2. In univariate analysis, D-dimer, fibrinogen, INR, prothrombin time, and activated partial thromboplastin time were each associated with OS (HR 1.33-1.38 per SD; all p < 0.05). Complex karyotype correlated with higher D-dimer (median 1.39 vs. 0.60 μg/mL, p = 0.022) and fibrinogen (3.91 vs. 2.53 g/L, p = 0.007), while TP53 variant allele frequency (VAF) showed modest positive correlations with D-dimer (ρ = 0.21), INR (ρ = 0.27), and PT (ρ = 0.27; all p < 0.05). Clustering identified three coagulation phenotypes: Silent (51%), Thrombo-inflammatory (31%), and Consumption-like (18%), showing a graded but statistically non-significant gradient in molecular features and a stepwise decline in median OS (14, 10 and 8 months; log-rank p = 0.041). After adjustment for complex karyotype, TP53 VAF, and favorable co-mutation count, the Consumption-like phenotype was associated with a non-significant increased risk (HR 1.83, 95% CI 0.92-3.65, p = 0.084), whereas favorable co-mutation pathways remained independently protective (HR 0.56, 95% CI 0.35-0.90, p = 0.016). CONCLUSION: In TP53-mutated AML/MDS, coagulation activation intensity is associated with the degree of genomic instability. The three phenotypes may add biological resolution beyond classical DIC and cytogenetic risk groups, but represent laboratory patterns rather than validated bleeding or thrombosis prediction tools. However, after accounting for genomic features, phenotypes were not independent predictors of outcome, with complex karyotype, TP53 VAF, and favorable co-mutation count driving prognosis. Because treatment intensity and other clinical confounders were not available, these survival associations are hypothesis-generating. Coagulation profiling remains inexpensive, widely accessible, and offers a practical window into disease biology that warrants prospective validation.

TP53↗

PubMed2005

Induced mitogenic activity in AML-12 mouse hepatocytes exposed to low-dose ultra-wideband electromagnetic radiation.

Ultra-wideband (UWB) technology has increased with the use of various civilian and military applications. In the present study, we hypothesized that low-dose UWB electromagnetic radiation (UWBR) could elicit a mitogenic effect in AML-12 mouse hepatocytes, in vitro. To test this hypothesis, we exposed AML-12 mouse hepatocytes, to UWBR in a specially constructed gigahertz transverse electromagnetic mode (GTEM) cell. Cells were exposed to UWBR for 2 h at a temperature of 23 degrees C, a pulse width of 10 ns, a repetition rate of 1 kHz, and field strength of 5-20 kV/m. UWB pulses were triggered by an external pulse generator for UWBR exposure but were not triggered for the sham exposure. We performed an MTT Assay to assess cell viability for UWBR-treated and sham-exposed hepatocytes. Data from viability studies indicated a time-related increase in hepatocytes at time intervals from 8-24 h post exposure. UWBR exerted a statistically significant (p < 0.05) dose-dependent response in cell viability in both serum-treated and serum free medium (SFM) -treated hepatocytes. Western blot analysis of hepatocyte lysates demonstrated that cyclin A protein was induced in hepatocytes, suggesting that increased MTT activity after UWBR exposure was due to cell proliferation. This study indicates that UWBR has a mitogenic effect on AML-12 mouse hepatocytes and implicates a possible role for UWBR in hepatocarcinoma.

Animals↗

PubMed2006

Concomitant inhibition of MDM2 and Bcl-2 protein function synergistically induce mitochondrial apoptosis in AML.

Disruption of Mdm2-p53 interaction activates p53 signaling, disrupts the balance of antiapoptotic and proapoptotic Bcl-2 family proteins and induces apoptosis in acute myeloid leukemia (AML). Overexpression of Bcl-2 may inhibit this effect. Thus, functional inactivation of antiapoptotic Bcl-2 proteins may enhance apoptogenic effects of Mdm2 inhibition. We here investigate the potential therapeutic utility of combined targeting of Mdm2 by Nutlin-3a and Bcl-2 by ABT-737, recently developed inhibitors of protein-protein interactions. Nutlin-3a and ABT-737 induced Bax conformational change and mitochondrial apoptosis in AML cells in a strikingly synergistic fashion. Nutlin-3a induced p53-mediated apoptosis predominantly in S and G2/M cells, while cells in G1 were protected through induction of p21. In contrast, ABT-737 induced apoptosis predominantly in G1, the cell cycle phase with the lowest Bcl-2 protein levels and Bcl-2/Bax ratios. In addition, Bcl-2 phosphorylation on Ser70 was absent in G1 but detectable in G2/M, thus lower Bcl-2 levels and absence of Bcl-2 phosphorylation appeared to facilitate ABT-737-induced apoptosis of G1 cells. The complementary effects of Nutlin-3a and ABT-737 in different cell cycle phases could, in part, account for their synergistic activity. Our data suggest that combined targeting of Mdm2 and Bcl-2 proteins could offer considerable therapeutic promise in AML.

Animals↗

PubMed2006

Mutation analysis of hCDC4 in AML cells identifies a new intronic polymorphism.

hCDC4 (FBW7, FBXW7) is a new potential tumor suppressor gene which provides substrate specificity for SCF (Skp-Cullin-F-box) ubiquitin ligases and thereby regulates the degradation of potent oncogenes such as cyclin E, Myc, c-Jun and Notch. Mutations in the hCDC4 gene have been found in several solid tumors such as pancreas, colorectal or endometrial cancer. We carried out a mutation analysis of the hCDC4 gene in 35 samples of patients with Acute Myeloid Leukemia (AML) to elucidate a possible role of hCDC4 mutations in this disease. By direct DNA sequencing and digestion with Surveyor nuclease one heterozygous mutation in the 5' untranslated region of exon 1, transcript variant 3 was detected. Additionally, we could identify a new intronic SNP downstream of exon 10. The new variation was present in 20% of AML samples and was furthermore confirmed in a panel of 51 healthy individuals where it displayed a frequency of 14%. In conclusion we provide first data that in contrast to several solid tumors, mutations in the hCDC4 gene may not play a pivotal role in the pathogenesis of AML. Furthermore, we describe a new intronic polymorphism with high frequency in the intron sequence of the hCDC4 gene.

Journal Article↗

PubMed1999

Double induction strategy for acute myeloid leukemia: the effect of high-dose cytarabine with mitoxantrone instead of standard-dose cytarabine with daunorubicin and 6-thioguanine: a randomized trial by the German AML Cooperative Group.

Early intensification of chemotherapy with high-dose cytarabine either in the postremission or remission induction phase has recently been shown to improve long-term relapse-free survival (RFS) in patients with acute myeloid leukemia (AML). Comparable results have been produced with the double induction strategy. The present trial evaluated the contribution of high-dose versus standard-dose cytarabine to this strategy. Between March 1985 and November 1992, 725 eligible patients 16 to 60 years of age with newly diagnosed primary AML entered the trial. Before treatment started, patients were randomized between two versions of double induction: 2 courses of standard-dose cytarabine (ara-C) with daunorubicin and 6-thioguanine (TAD) were compared with 1 course of TAD followed by high-dose cytarabine (3 g/m2 every 12 hours for 6 times) with mitoxantrone (HAM). Second courses started on day 21 before remission criteria were reached, regardless of the presence or absence of blast cells in the bone marrow. Patients in remission received consolidation by TAD and monthly maintenance with reduced TAD courses for 3 years. The complete remission (CR) rate in the TAD-TAD compared with the TAD-HAM arm was 65% versus 71% (not significant [NS]), and the early and hypoplastic death rate was 18% versus 14% (NS). The corresponding RFS after 5 years was 29% versus 35% (NS). An explorative analysis identified a subgroup of 286 patients with a poor prognosis representing 39% of the entire population; they included patients with more than 40% residual blasts in the day-16 bone marrow, patients with unfavorable karyotype, and those with high levels of serum lactate dehydrogenase. Their CR rate was 65% versus 49% (p =.004) in favor of TAD-HAM and was associated with a superior event-free survival (median, 7 v 3 months; 5 years, 17% v 12%; P =.012) and overall survival (median, 13 v 8 months; 5 years, 24% v 18%; P =.009). This suggests that the incorporation of high-dose cytarabine with mitoxantrone may contribute a specific benefit to poor-risk patients that, however, requires further substantiation. Double induction, followed by consolidation and maintenance, proved a safe and effective strategy and a new way of delivering early intensification treatment for AML.

Adolescent↗

PubMed2000

[Effect of etoposide added to individualized induction therapy of adult acute myeloid leukemia--the JALSG-AML-92 Study. Japan Adult Leukemia Study Group].

A multicenter prospective randomized study was undertaken to assess the efficacy of etoposide added to the standard remission induction therapy for acute myeloid leukemia (AML). Consecutively registered newly diagnosed adult AML patients were randomized to receive either daunorubicin (40 mg/m2/day x 4 or more), behenoyl cytarabine (200 mg/m2/day x 10 or more) and 6-mercaptopurine (70 mg/m2/day x 10 or more) (BH-AC-DM), or the same three drugs plus etoposide (100 mg/m2/day x 5) (BH-AC-EDM) for response-oriented individualized induction therapy. The patients achieving complete remission (CR) received the same 3 courses of consolidation therapy followed by 6 courses of maintenance/intensification therapy. M3 was excluded and M0 was included. Of 667 patients registered, 655 were evaluable. The median age was 49 years (range, 15 to 85). CR rates were 77% in the BH-AC-DM group and 75% in the BH-AC-EDM group. In M4 patients, CR rates were 86% and 69% (p = 0.009), and, in M5, 80% and 77% (p = 0.810) in the BH-AC-DM and BH-AC-EDM groups, respectively. The predicted 6-year overall survival rates were 30% and 38% for BH-AC-DM and BH-AC-EDM groups, and the disease-free survival (DFS) rates of CR patients were 25% and 35% (p = 0.925), respectively. In conclusion, the present study failed to show any advantage of the addition of etoposide to the standard individualized induction therapy in adult AML, even among M4 and M5. These above data have already been published in the Int J Hematol (70: 87-104, 1999).

Adolescent↗

PubMed2001

The AML1/MTG8 Fusion Transcript in t(8;21) Positive AML and its Implication for the Detection of Minimal Residual Disease; Malignancy.

The reciprocal translocation t(8;21)(q22;q22) is one of the most frequent chromosomal aberrations in acute myeloblastic leukemia (AML). At the molecular level, this aberration rearranges the gene for the AML1-transcription factor on chromosome 21, which is essential for normal hematopoiesis, to the MTG8 gene on chromosome 8, thereby leading to a specific AML1/MTG8 fusion mRNA. This fusion gene is involved in leukemogenesis presumably by interfering with normal AML1-dependent transcriptional regulation. AML patients with t(8;21) have a favourable response to chemotherapy and a relatively good prognosis after intensive consolidation treatment with high dose AraC or autologous stem cell transplantation. RT-PCR for the specific AML1/MTG8 fusion transcripts can be used for the sensitive detection of residual leukemic cells during and after therapy. However, since a considerable proportion of these patients shows a positive PCR result even in long-term complete hematological remission, the prognostic value of qualitative PCR methods is doubtful. In contrast, quantitative PCR methods might be able to identify patients with a high risk of relapse by serial quantification of minimal residual disease (MRD). Because of its high degree of standardisation and automation, the recently developed real time PCR method can be used for the valid and reproducible detection of MRD in large prospective trials. This technology offers the potential to define the antileukemic efficiency of different treatment elements and the prognostic value of MRD in patients with t(8;21) positive AML.

Journal Article↗

PubMed2001

[Prognostic significance of cytogenetic changes in patients with acute myeloid leukemia (AML). (Analysis of results in 105 patients treated at the Hemato-oncology Clinic of the University Hospital in Olomouc from 1997 to 2000].

Chromosomal aberrations are one of the most important prognostic factors in patients with acute myeloid leukemia (AML). This work present analysis of conventional cytogenetic results completed by fluorescence in situ hybridization (FISH) obtained from 105 patients in the time of diagnosis of AML. The median age of patients was 51 years (range 19-79 years), with slight predominance of women (female to male ratio 1.2:1). The evaluated group involved all patients with AML diagnosis, treated by intensive induction chemotherapy in the Department of Hematology-oncology, University Hospital, Olomouc during last 4 years with assessable cytogenetic results. Chromosomal changes were found in 63 (60%) patients. The most often affected chromosomes in succession of frequency were 8, 17, 7, 5, 11, 15, 16 a 21. Based on found specific and frequent chromosomal changes the patients were divided into 3 prognostic subgroups and the significance of chromosomal aberrations was evaluated. The subgroup of 17 patients with good prognosis consisted of a patients with acute promyelocytic leukemia with translocation t(15;17), 4 patients with t(8;21) and 4 patients with inv(16). 14 patients of 17 live in complete remission, median of overall survival (OS) is 63 weeks. The subgroup of intermediate prognosis was formed by 60 patients, 42 had normal karyotype and 18 patients had other chromosomal abnormalities. Median OS of this group was 35 weeks. The third subgroup with poor prognosis consisted of 28 patients with changes of chromosomes 3, 5, 7, 11 and complex karyotype. 64.3% of patients received complete remission and median OS was 35 weeks. Statistical evaluation of OS showed significant difference (p = 0.002) in subgroup with good prognosis versus subgroup with poor prognosis and in subgroup with good prognosis versus subgroup with intermediate prognosis (p = 0.014). Statistical significance of OS in subgroup with intermediate prognosis versus subgroup with poor prognosis was not proved (p = 0.34), but fit appeared in evaluation of both groups in patients under 55 years. It seems that in patients in age 55 and more the age is independent poor prognostic factor and findings of chromosomal aberrations do not significantly influence prognosis.

Acute Disease↗

PubMed2000

[The Feature of Skewing Distribution of TCR Vbeta T Cells from Peripheral Blood and Bone Marrow in Patients with AML-M(5)]

The TCR Vbeta 24 subfamily genes were amplified in peripheral blood and bone marrow mononuclear cells from 5 cases with acute monocytic leukemia (AML-M(5)) using RT-PCR, to observe the distribution of TCR Vbeta subfamilies. The results indicated that 1 - 19 Vbeta subfamily T cells could be identified in different samples from AML-M(5) cases. The variation of distribution of TCR Vbeta subfamily T cells could be found in different individual samples. The results provided the feature of cell immune function change in skewed distribution of TCR Vbeta subfamily T cells from peripheral blood and bone marrow of patients with AML-M(5).

Journal Article↗